Using latest version of Discourse, issue happened on previous version too.
Topics appear normally in some e-mail clients while others show text/html content that does not show the blank lines. It displays text/html content without empty/blank lines (versus what is displayed in the forum and in the text/plain content of the raw message).
I was able to see the raw messages Discourse sends as multipart/alternative that include:
text/plain – shows blank lines between paragraphs
text/html – no blank lines between paragraphs
It is necessary for text/html to reproduce the blank line spacing as the user has created it (or as close as possible) since it improves readability and users should not have to ask why their content is modified. E-mails coming into Discourse are converted to plain text and it preserves a single blank line such as would be found between paragraphs. in the text/html I do see line break characters (br) as well as the use of § to signal a paragraph change.
To explain further, here is a sample as it would appear in the e-mail Discourse sends out:
text/plain: This is a line of text. There is one blank line immediately above this line. text/html: <p style="margin-top:0; border: 0;">This This is a line of text.</p> <p style="margin-top:0; border: 0;">There is one blank line immediately above this line.</p>
The result displayed based on the text/html shows:
This is a line of text.
There is one blank line immediately above this line.
Is it possible that the text/html could be modified so that the margin-top attribute is set to something other than 0?
Okay, having spent a bit more time, I find this issue has been present in Yahoo Mail since around 2010/2011 and is something a major percentage of users are going to experience. It really needs to be addressed. Here is more information including some suggestions as to ways to format the Discourse text/html so that it will properly render the paragraphs:
I think the best suggestion I have seen may be to add margin-bottom:1em – could someone comment on whether this can be done, and if this is not considered a bug, please suggest where it should be posted to get it resolved?